1. Field of the Invention
The present invention relates to an image display apparatus for displaying an image by selectively emitting light from a plurality of regularly arranged semiconductor light emitting elements.
2. Description of the Related Art
A large-sized image display apparatus (LED display) which includes a plurality of semiconductor light emitting elements (LEDs) arranged two-dimensionally is practically used. In general, the LEDs in the LED display are bullet-shaped LED modules, each of which has an LED chip sealed with a resin or the like. However, since the bullet-shaped LED modules are large in size and each module has a diameter of about 3 mm, it is required that the modules are soldered to a mount substrate one by one and an arrangement pitch (pixel pitch) of the bullet-shaped LED modules is at least about 10 mm. For this reason, no bullet-shaped LED modules are available for a small-sized LED display.
For example, Japanese Patent Application Kokai Publication No. 2002-62825 as Patent Document 1 proposes an LED display with a smaller pixel pitch in order to realize downsizing and high definition. In this document, LED elements are arranged on a mount substrate, by forming the LED elements as display elements on a wafer, and repeating steps of separating the LED elements into pieces and then transferring the separated LED elements on the mount substrate.
However, since a mount substrate on which LED elements are to be formed on a wafer are mounted has matrix wiring composed of anode conductive wiring layers and cathode conductive wiring layers and a pixel pitch is very small, a permissible margin of a mount position of each LED element in an LED display is extremely small. For this reason, even if the mount position of the LED element is slightly shifted, there is a probability that a short circuit between the conductive wiring layers occurs because of the shifted LED element.
In a case to use fluid die-bonding paste for fixing LED elements on a mount substrate, even if a mount position of an LED element is not shifted, there is a probability that a short circuit between the conductive wiring layers occurs because of the die-bonding paste pressed out from between the LED element and the mount substrate.